一种仿生感觉毛气流传感器

模仿昆虫感觉毛的结构,设计制备了表面对称电极含金属芯PVDF气流传感器SMPF(Symmetric Metal core PVDF Fiber).利用自制的拉制纤维设备,制备了SMPF胚体.在表面涂镀对称电极后,经过高温极化、电极封装等工艺后,成功制备了SMPF气流传感器.基于第1类压电方程和流体力学理论,建立了悬臂梁结构的SMPF气流传感模型,分析了传感器输出信号与纤维长度、气流速度以及气流作用方向之间的关系.将悬臂梁结构的SMPF安置在气流流场中,进行冲击气流测试实验.实验结果表明,SMPF气流传感器的输出信号与纤维长度成非线性关系,与气流速度成平方关系,与气流作用方向成"8"字形关系.实验结果验证了理论模型,表明SMPF传感器能够感知气流的速度和作用方向,具有较广泛的工程应用前景.     

表面四电极含金属芯压电纤维的冲击振动传感特性研究

模仿昆虫毛发感受器的结构和功能,设计制备了一种能测量外部振动的表面四电极含金属芯压电纤维(FMPF)冲击振动传感器.采用干压成型法制备了含铂金芯的压电陶瓷纤维胚体,经过高温烧结、涂镀表面电极、高温极化后,制成FMPF传感器.基于压电方程和振动理论,建立了悬臂梁结构的FMPF冲击振动传感器的理论模型,分析了传感信号与冲击振动角度和幅值的关系.把FMPF固定在基体上,搭建了实验系统,测试了FMPF对冲击振动的响应,验证了理论模型.结果表明,FMPF的传感信号和冲击振动的幅值成线性关系,和方向成"8"字形关系.得出了FMPF传感器能够测量冲击振动幅值和方向的结论.     

半电极含金属芯压电纤维的动态微力传感器

半电极含金属芯压电纤维(HMPF)是一种新型压电传感器.建立了HMPF的动态微力传感理论模型.根据第一类压电方程,基于振动理论,用平均电荷方法,推导出悬臂梁结构HMPF自由端受到垂直动态微力作用后,产生电荷的解析表达式;分析了长度和半径比对产生电荷的影响.实验结果表明,HMPF可以测量动态微力的频率和幅值,具有较高的动...     

仿生耳石器的冲击与振动传感特性研究 �

为了研究人体耳石器官的冲击与振动传感特性,本文根据人体耳石器官的生理结构,采用表面对称电极含金属芯PVDF压电纤维(SMPF)作为元件,设计制备了仿生耳石器。根据压电方程和振动理论,建立了仿生耳石器的冲击和振动传感理论模型,搭建实验平台,测试了仿生耳石器的振动传感功能。实验结果证明,在冲击与振动的作用下?仿生耳石器中的液体使耳石器内的囊斑发生形变,通过SMPF产生的电荷信号,可以感知受到冲击和振动的波形、频率和振幅。实验结果验证了理论模型,同时证明了人体耳石器具有感知直线加速度的幅值和角度的特性。     

一种仿生壶腹嵴的振动传感特性研究

为了研究人耳半规管中壶腹嵴的振动传感特性,本文采用表面对称电极含金属芯PVDF纤维(SMPF)传感器,代替人体纤毛细胞感受器,并模仿人体壶腹嵴的结构,设计制备了一种仿生壶腹嵴。根据压电方程和振动理论,建立了仿生壶腹嵴的振动传感理论模型。搭建了实验系统,测试了仿生壶腹嵴的振动传感功能。实验结果表明,仿生壶腹嵴在液体压力作用下可以产生相应的变形,而通过SMPF的输出电荷信号,可以感知仿生壶腹嵴受到的振动激励,包括正弦与冲击振动的波形、频率和幅值。实验结果验证了理论模型,同时验证了人体半规管中,壶腹嵴具有振动感知的能力和作用。     

含金属芯压电纤维传感Lamb波方向性研究

含金属芯压电纤维(MPF)是一种新型压电功能器件.阐述了基于小波变换的Lamb波能量因子计算原理,把MPF作为Lamb波传感器,分别采用幅值和小波变换能量因子的方法对MPF传感Lamb波的方向性进行了研究.研究结果表明:MPF对Lamb波的传感表现出很强的方向性.相比采用幅值表征的结果,采用能量因子进行传感方向性表征更...     

压电纤维复合材料悬臂梁发电性能分析

研究了压电纤维复合材料悬臂梁俘能器的电学特性,使用有限元法分析了叉指型电极结构尺寸、压电纤维和基板材料厚度对输出电压的影响,并将同等尺寸的d33和d31模式压电纤维材料悬臂梁俘能器发电能力进行对比分析.结果表明:叉指电极结构尺寸对工作于d33模式的压电纤维材料悬臂梁俘能器输出电压影响较大.d33模式俘能器具有能产生高电压、低电流值的特点,当压电纤维和基板材料的最佳厚度比为0.75时,俘能器产生电荷量最大.而d31模式俘能器具有能产生低电压、高电流值的特点,当压电纤维和基板材料的最佳厚度比为0.6时,俘能器的输出电压最大.相对于d33模式压电纤维材料,工作于d31模式压电纤维材料更适合作为发电材料使用.     

使用压电薄膜的指纹传感器

提供了一种通过将作用于压电薄膜的压力转换成电信号来感知指纹的指纹传感器。该指纹传感器具有一个压电器件集合体，由下及上分别为衬底、下部电极、压电薄膜、上部电极、加压部分以及在下部电极上形成的非导电层。加压部分用于通过由于指纹接触所产生的压力来改变压电薄膜上的电荷量；非导电层用于支撑和暴露加压部分。该指纹传感器结构简单，并且能够利用压电现象准确感知指纹信息，故可广泛应用于公共机构和私人企业中用于确定人员身份的系统以及个人便携系统。     

扭转效应下石英晶片电荷量及其灵敏度分布规律研究

针对石英晶体在扭转、复合变形等三维复合压电效应还没有建立起完整的压电效应理论体系,在扭转效应下如何确定检测电极的分布位置使电荷灵敏度达到最大的研究较少。文章通过研究扭转测量晶组的组成,采用分割电极法将检测电极布置到最大灵敏度方向,实现对不同扭矩作用下电荷量的实验测量并分析测量误差,而通过对扭转电荷灵敏度分布规律的理论计算与实验分析确定检测电极布置的最大灵敏度方向。实验结果说明,石英晶片在扭转效应下电极电荷量与扭矩成线形关系,当电极分割线须与坐标系的y轴重合时扭转电荷灵敏度最大,该研究将为设计新型扭矩传感器检测电极的位置确定提供理论基础。     

涡街流量计的压电探头最优距离和新型测量方法研究

针对涡街式流速传感器中电信号微弱并且提取特征涡街信号困难,基于压电方程和湍流N-S方程,建立了流-固-电耦合仿真计算模型,构建了流速测量的新方法.通过理论分析和风洞实验,获得了圆柱绕流体直径(D)、空气流速(v)与压电传感距离(L)以及功率(P)之间的影响规律.仿真计算和实验结果表明:通过提取频域曲线中涡激频率下的功率作为涡街的传感强度,有助于感知微弱的空气流速信号,同时解决噪声等电路上的干扰影响.其次,D增加,最优传感距离(Losr)增加;D不变时,功率(Posr)随流速增大而提高,且Losr不变;通过分析得出了采集信号在Losr下最优的本质原因—在该处,涡街成熟且脱落稳定、升力系数(CL)稳定.最后,该压电装置测量的最低流速为0.3 m/s.     

Design and characterization of MEMS-based flow-rate and flow-direction microsensor

This study designs and characterizes a novel MEMS-based flow-rate micro-sensor consisting of a platinum resistor deposited on a silicon nitride-coated silicon cantilever beam. Due to the difference between the thermal conductivities of the silicon nitride film and the silicon beam, the tip of the cantilever structure bends slightly in the upward direction. As air travels across the upper surface of the sensor, it interferes with the curved tip and displaces the beam in either the upward or the downward direction. The resulting change in the resistor signal is then used to calculate the velocity of the air. A flow-direction micro-sensor is constructed by arranging eight cantilever structures on an octagonal platform. Each cantilever is separated from its neighbors by a tapered baffle plate connected to a central octagonal pillar designed to attenuate the aerodynamic force acting on the cantilever beams. By measuring the resistor signals of each of the cantilever beams, the micro-sensor is capable of measuring both the flow rate and the flow direction of the air passing over the sensor. A numerical investigation is performed to examine the effects of the pillar height and pillar-to-tip gap on the airflow distribution, the pressure distribution, the bending moment acting on each beam, and the sensor sensitivity. The results show that the optimum sensor performance is obtained using a pillar height of 0.75 mm and a pillar-to-tip gap of 5 mm. Moreover, the sensitivity of the octagonal sensing platform is found to be approximately 90% that of a single cantilever beam.     

A microcantilever-based gas flow sensor for flow rate and direction detection

Utilizing conventional micro-electro-mechanical systems techniques, this study fabricates and characterizes a novel micro gas flow sensor comprising four silicon nitride/silicon wafer cantilever beams arranged in a cross-form configuration. The residual stresses induced within the beams during their fabrication cause the tip of each beam to curve slightly in the upward direction. However, as air travels over the surface of the sensor, the upstream cantilevers are deflected in the downward direction, while the downstream cantilevers are deflected in the upward direction. The velocity of the air flow is then determined by measuring the corresponding change in resistance of the piezoresistors patterned on the upper surface of each cantilever beam. It is shown that by measuring the change in resistance of all four cantilever beams, the proposed sensor can detect not only the velocity of the air flow, but also its direction.     

Integration of displacement sensor into bulk PZT thick film actuator for MEMS deformable mirror

Bulk PZT thick film actuator integrated with displacement sensor, the so-called self-sensing actuator, is presented in this paper. The PZT film is used as not only an actuating layer but also a displacement sensor, which is achieved by dividing the electrode on the top surface of the PZT film into two parts: central top electrode for actuating and outer annular sensor electrode for piezoelectric displacement detection. When the actuator moves, the piezoelectric charge is induced in the outer annular PZT due to the piezoelectric effect. The total amount of accumulated charge is proportional to the stress acting on the PZT, which is in turn proportional to the actuator displacement. By collecting the piezoelectric charge, the actuator displacement can be detected. A theoretical model is proposed to determine the structure parameters of the sensor and predict the sensor sensitivity. Experiments were performed on the micro-fabricated sensor integrated PZT thick film actuator, and the measured piezoelectric charge is close to the theoretical predictions. The integrated piezoelectric sensor has a displacement sensitivity of approximately 4 pC/nm. In addition, the integration of displacement sensor into the actuator needs no additional fabrication process and has no influence on the actuator performances.     

变宽度悬臂梁的FBG流速传感器

通过对光纤传感器进行设计,提出了一种基于变宽度悬臂梁的光纤(Bragg)光栅(FBG)流速传感器.传感部分由不锈钢材质的悬臂梁和粘贴在其特定位置上的FBG构成,悬臂梁采用等腰梯形和矩形相结合的外形结构设计,传感头两部分之间的衔接不需要用销子固定,整个传感头浑然一体,无额外附加重量,制作方法简易,且实验设置参考光栅,实验结果不受温度变化的影响.实验表明:传感器的Bragg波长漂移量与流速变化有很好的线性关系,传感器的灵敏度为0.025 m/s.可测流速范围为0～2 m/s,传感器不仅实现了对温度的补偿,而且提高了测量精度、灵敏度.     

压电传感器现场监测石英表面电荷分布

理论上解析了石英表面电荷分布情况,利用双液隔电极压电传感器(ESPS)与溶液直接接触的特点,对阴、阳离子表面活性剂的吸附情况进行了现场监测,间接地证明了理论分析,这对传感器本身以及石英表面改性处理有重要参考价值。     

Active vibration control of smart piezoelectric beams: Comparison of classical and optimal feedback control strategies

This paper presents a numerical study concerning the active vibration control of smart piezoelectric beams. A comparison between the classical control strategies, constant gain and amplitude velocity feedback, and optimal control strategies, linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controller, is performed in order to investigate their effectiveness to suppress vibrations in beams with piezoelectric patches acting as sensors or actuators. A one-dimensional finite element of a three-layered smart beam with two piezoelectric surface layers and metallic core is utilized. A partial layerwise theory, with three discrete layers, and a fully coupled electro-mechanical theory is considered. The finite element model equations of motion and electric charge equilibrium are presented and recast into a state variable representation in terms of the physical modes of the beam. The analyzed case studies concern the vibration reduction of a cantilever aluminum beam with a collocated asymmetric piezoelectric sensor/actuator pair bonded on the surface. The transverse displacement time history, for an initial displacement field and white noise force disturbance, and point receptance at the free end are evaluated with the open- and closed-loop classical and optimal control systems. The case studies allow the comparison of their performances demonstrating some of their advantages and disadvantages.     

地下金属管线无损检测仪中涡流传感器的阻抗分析

根据电磁涡流检测原理,对地下金属管线无损检测仪中的涡流传感器进行设计,并针对无损检测仪中涡流传感器线圈结构参数对传感器性能的影响进行分析。建立空心线圈的有限元模型,对线圈尺寸影响因素进行了分析。针对不同的结构参数,确定磁芯半径与传感器线圈阻抗变化的关系式,确定传感器线圈参数对于传感器线性度和灵敏度的影响,为涡流传感器的...